GeneralHELP-Four digit security code for bluetooth?

Hi all, I have just purchased a 2006 accord ex, the car has both sat nav and Bluetooth, the problem I am getting is that when I try to pair my phone with the cars Bluetooth, the system is saying that it is locked? I have tried all the normal codes i.e 1234, 9999 0000 etc, but no joy. the independent dealer I purchased the car from can't help and I don't have the previous owners number to call. I am thinking my only option is to go to a Honda dealer and see if they will tell me the code or reset the system, any other suggestions or is this the only way?